Numerical storm surge model with higher order finite difference method of lines for the coast of Bangladesh

In this study, the method of lines (MOLs) with higher order central difference approximation method coupled with the classical fourth order Runge-Kutta (RK(4,4)) method is used in solving shallow water equations (SWEs) in Cartesian coordinates to foresee water levels associated with a storm accurately along the coast of Bangladesh. In doing so, the partial derivatives of the SWEs with respect to the space variables were discretized with 5-point central difference, as a test case, to obtain a system of ordinary differential equations with time as an independent variable for every spatial grid point, which with initial conditions were solved by the RK(4,4) method. The complex land-sea interface and bottom topographic details were incorporated closely using nested schemes. The coastal and island boundaries were rectangularized through proper stair step representation, and the storing positions of the scalar and momentum variables were specified according to the rules of structured C-grid. A stable tidal regime was made over the model domain considering the effect of the major tidal constituent, M₂ along the southern open boundary of the outermost parent scheme. The Meghna River fresh water discharge was taken into account for the inner most child scheme. To take into account the dynamic interaction of tide and surge, the generated tidal regime was introduced as the initial state of the sea, and the surge was then made to come over it through computer simulation. Numerical experiments were performed with the cyclone April 1991 to simulate water levels due to tide, surge, and their interaction at different stations along the coast of Bangladesh. Our computed results were found to compare reasonable well with the limited observed data obtained from Bangladesh Inland Water Transport Authority (BIWTA) and were found to be better in comparison with the results obtained through the regular finite difference method and the 3-point central difference MOLs coupled with the RK(4,4) method with regard to the root mean square error values.     

4个地理群体魁蚶（Scapharca broughtonii）的形态差异与判别分析

运用多变量形态度量学分析方法对韩国统营、山东黄岛、山东蓬莱、江苏前三岛4 个地理区域的魁蚶（Scapharca broughtonii Schrenck）种群间的形态变异进行了研究。单因素方差分析（ANOVA）和Tukey 检验表明, 魁蚶不同地理种群表现出显著形态变异（P〈0.05）。聚类分析结果表明, 黄岛和前三岛...     

应用新一代测序技术测定大室别藻苔虫线粒体基因组全序列

线粒体基因组的获得传统上通常是采取长PCR结合鸟枪法或步移法测序。近年来新一代测序技术蓬勃发展,以454,Solexa和SOLiD测序平台为代表。应用新一代高通量测序技术(Solexa)并结合巢式PCR扩增,完成了大室别藻苔虫(Membranipora grandicella)的线粒体基因组全序列。大室别藻苔虫线粒体基因组是目前国际上获得的第一条苔藓动物软壁亚目线粒体基因组全序列,基因组全长为15861 bp,比已完成的4种苔藓动物线粒体基因组略大。大室别藻苔虫线粒体基因组包含13个蛋白质编码基因、2个核糖体RNA基因和20个转运RNA基因。通过与已测得的苔藓动物进行比较,发现目前已完成的5个苔藓动物线粒体基因组的基因排列顺序显著不同。苔藓动物线粒体基因组基因排列的比较,今后可能会成为探讨该类群系统演化关系的重要信息来源。     

基于LGR的不规则MODFLOW模型嵌套技术研究

在美国地调局开发的MODFLOW局部网格加密技术(简称LGR)的基础上,针对LGR程序不能应用于不规则区域模型嵌套的局限性展开研究。对LGR程序源代码进行分析,探讨在不规则模型嵌套中出现的问题并研究解决方案。利用FORTRAN语言对LGR源代码进行二次开发,增加模型边界匹配程序、修改参数调整程序、改编水头和流量传递程序,生成新的模型嵌套程序LGR2.1。建立多种嵌套模型对改编后程序进行验证,模拟结果表明:该程序可以模拟单区域和多区域的不规则嵌套模型,模拟结果正确可靠;应用该程序可以对模型内部和边界处的局部区域进行加密嵌套,在减少模拟时间和贮存空间的情况下提高模拟的精度。     

面向稀疏降水站点的套合各向异性贝叶斯地统计估计研究

由于形成过程中各种影响因素在不同尺度上的运行和相互作用,降水的空间变异普遍是发生在多尺度上地理过程叠加后的结果。建立较好地反映该动力学过程的多尺度复杂空间模型对于区域降水变量估计和空间分析是很有必要的,尤其是面向稀疏监测区域。贝叶斯地统计模型具有多尺度结构化建模的能力,提供了一种可以融合观测值(含有误差的外在实现)、未知变量、先验信息和复杂数据模型(隐藏的真实过程)的统计推断框架。鉴于降水现象在尺度和各向异性上的叠加特征,本研究将基于贝叶斯和地统计的理论和方法探讨二维随机场中存在的套合各向异性分解估计的可行性,并在对每个独立组分贡献定量计算的基础上,进一步分析和挖掘套合各向异性模型在降水插值中的应用潜力。结果表明:通过贝叶斯方法,稀疏数据中叠置的多尺度性和多方向性通过地统计套合模型可以得到有效的分解;复杂套合模型估计具有向下兼容简单套合模型的能力;套合各向异性协方差结构的使用对于区域降水插值的精度提升具有明显作用。     

海洋环流模式的发展和应用Ⅱ.近海和区域环流模式

回顾了近20年来中国科学院大气物理研究所大气科学和地球流体动力学数值模拟国家重点实验室近海和区域海洋环流模式发展和应用的历程.介绍了正压区域海流模式在中国近海海流数值模拟研究当中的应用以及一个24层、最高水平分辨率为0.25°×0.25°的三重嵌套的中国近海环流模式及其应用.在嵌套模式基础上,基于变分原理,建立了一个中国近海环流的资料同化分析系统.初步结果表明,资料同化提高了模式计算的真实性,所揭示的黑潮的强度和流幅、夏季黄海冷水团的位置等都更接近观测结果.     

GRAPES伴随模式底层数据栈优化

GRAPES伴随模式是其四维变分同化系统的核心组成部分。由于其计算过程复杂,临时数据较多,实现中采用断点存储策略可以有效减少伴随模式的计算时间和存储空间。极限断点存储策略是在单积分步内以全存储策略实现为基础,将其中部分基态以计算代替的一种类断点存储策略。在该策略的支持下,需要一种新的数据管理结构,来保证程序的正确运行。文章提出了在已有栈基础上优化的新数据存储管理方式——嵌套多链栈,这种结构可有效满足使用极限断点存储技术实现GRAPES伴随模式的初态管理需求。试验表明:相比断点存储技术,在总内存增加不超过30%的情况下可使GRAPES的运行效率提高1倍。     

多维邻近性与城-城流动人口的流入地选择——基于嵌套Logit模型的实证分析

基于2017年中国流动人口动态监测调查数据,采用嵌套Logit模型分析了地理、制度、信息和知识等多维邻近性对城-城流动人口流入地选择的影响.结果 表明:城-城流动人口倾向于流入与户籍地地理相邻、制度相似、信息联系密切以及与自身知识水平相匹配的城市,这在一定程度上缓解人口向工资水平高、就业机会多和公共服务水平好的大城市集...     

Response time and water origin in a steep nested catchment in the Italian Dolomites

In this study, we investigate the surface flow time of rise in response to rainfall and snowmelt events at different spatial scales and the main sources originating channel runoff and spring water in a steep nested headwater catchment (Rio Vauz, Italian Dolomites), characterized by a marked elevation gradient. We monitored precipitation at different elevations and measured water stage/streamflow at the outlet of two rocky subcatchments of the same size, representative of the upper part of the catchment dominated by outcropping bedrock, at the outlet of a soil‐mantled and vegetated subcatchment of similar size but different morphology, and at the outlet of the main catchment. Hydrometric data are coupled with stable isotopes and electrical conductivity sampled from different water sources during five years, and used as tracers in end‐member mixing analysis, application of two component mixing models and analysis of the slope of the dual‐isotope regression line. Results reveal that times of rise are slightly shorter for the two rocky subcatchments, particularly for snowmelt and mixed rainfall/snowmelt events, compared to the soil‐mantled catchment and the entire Rio Vauz Catchment. The highly‐variable tracer signature of the different water sources reflects the geomorphological and geological complexity of the study area. The principal end‐members for channel runoff and spring water are identified in rainfall and snowmelt, which are the dominant water sources in the rocky upper part of the study catchment, and soil water and shallow groundwater, which play a relevant role in originating baseflow and spring water in the soil‐mantled and vegetated lower part of the catchment. Particularly, snowmelt contributes up to 64 ± 8% to spring water in the concave upper parts of the catchment and up to 62 ± 11% to channel runoff in the lower part of the catchment. These results offer new experimental evidences on how Dolomitic catchments capture and store rain water and meltwater, releasing it through a complex network of surface and subsurface flow pathways, and allow for the construction of a preliminary conceptual model on water transmission in snowmelt‐dominated catchments featuring marked elevation gradients.     

PROSPECTING EXPLORATION

正20141266Fan Chaoyan(Guangdong Provincial Key Laboratory of Mineral Resources and Geological Processes,Guangzhou 510275,China);Wang Zhenghai On Error Analysis and Correction Method of Measured Strata Section with Wire Projection Method(Journal of